Habitica MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of behavioral disclosure but provides none. 'Cast spell' doesn't indicate whether this is a read-only operation or has side effects, what permissions or resources are required, whether it consumes spell slots or mana, what happens on success/failure, or any rate limits. For a tool that presumably performs a magical action in a game system, this complete lack of behavioral information is severely inadequate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

While 'Cast spell' is certainly concise, it represents under-specification rather than effective brevity. The two-word description fails to provide the necessary information an AI agent needs to understand and use this tool appropriately. Every word should earn its place, but here the description is so minimal that it doesn't fulfill its basic purpose of explaining what the tool does beyond its name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity implied by a spell-casting tool in what appears to be a game system, the description is completely inadequate. With no annotations, no output schema, and a minimal description that doesn't explain what casting actually does, what the expected outcomes are, or how this integrates with the broader game mechanics visible in sibling tools, this description fails to provide the contextual completeness needed for effective tool use.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema has 100% description coverage, with both parameters documented in the schema itself. The description adds no additional information about what spellId represents (is it a spell name, code, or learned spell reference?) or what targetId is used for (creature, location, or self?). While the schema provides the baseline documentation, the description doesn't enhance understanding of parameter meaning or usage context beyond what's already in the structured fields.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description 'Cast spell' is essentially a tautology that restates the tool name without adding meaningful context. While it identifies the action (cast) and resource (spell), it doesn't specify what casting a spell actually does in this system or how it differs from other magical actions that might exist. The description fails to distinguish this tool from potential alternatives like 'activate_spell' or 'invoke_spell' that might have different mechanics.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides absolutely no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (like having the spell learned or sufficient mana), appropriate contexts (combat vs. utility), or what makes casting different from other magical actions. Given the sibling tools include various game mechanics like buying items, feeding pets, and scoring tasks, the description offers no help in determining when spell-casting is the appropriate choice.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.